algae in our aquariums is distinguished by general appearance usually.
thread & hair algae (same stuff) it's long, thin strands that grow in the tank, you can see how the water if flowing if your curious, ... "algae eaters" are usually referring to fish & critters that eat this stuff, ... possibly this stuff only. (doesn't mean they'll touch anything else - unless otherwise stated)
staghorn and cladophora algae grow similar to each other, they're both branchy and fluffy like, one is a nice green and it stinks (clado), the other is only "greenish", it's not quite as bushy, it's tougher, doesn't stink, ... things will actually eat this (staghorn)
it all just turns into looks. and for the most part this is close enough for figuring out how to deal with it, what works & what doesn't.
if your after something specific, inquire with friends, chop it up, tear it up, throw it in your tank... then it's like a viral infection. your tank will have that always forever after, you may be able to get rid of the appearance, but never be fully rid of it. if the conditions are right and nothing is present to keep a particular algae in check it will spread like wildfire.
if your not going to be so gung-ho, whatever sample you obtain would be great growing in aquarium water by the window.
+1 on everything, except that clado stinks.
while im sure some of it does, there are a lot of different species of clado. the stuff i have doesnt have much of a smell to it at all. its kinda like categorizing all primates as having a prehensile tail.
the clado i have is pretty tough stuff, but my shrimp happily eat it. they wont eat the larger older strands, but they will eat new growth. over time, the affect is a nicely trimmed patch of algae that can end up looking kinda like flat marimo algae patches.
without something to keep it trimmed, however, it takes over everything. the algae on the snail is actually a kind of BBA. the strands never get very long.
if you look at the front of the snail you can see a little staghorn algae. some of the snails i have only have this kind. most of them are pond snails, and it can look kinda funny sometimes when the staghorn grows a nice big clump on their backs.